The invention relates to methods of inhibiting oxidative degradation of pharmaceutical formulations comprising at least one oxidation-susceptible active drug ingredient and to pharmaceutical formulations comprising oxidation-inhibiting excipients.
The desirability of providing pharmaceutical formulations in which an oxidation-susceptible active drug ingredient or ingredients are protected against oxidative degradation inherent to prolonged storage is a concept well known to, and appreciated by, one of ordinary skill in the art. Anti-oxidants commonly employed in various pharmaceutical formulations may include, inter alia, vitamin E, ascorbic acid, BHT (butylated hydroxytoluene), BHA (butylated hydroxyanisole), and the like.
Pharmaceutical formulations comprising ferrous ion sources as nutritional supplements are generally well known in the art. The presence of ferrous ion sources in pharmaceutical formulations has additional utility in other capacities. For example, it has been reported that preservation of oral liquid preparations from bacterial contamination can be achieved by treatment with, inter alia, certain ferrous sulfate/methylparaben mixtures. See H. van Doorne, et al., Pharmacy World and Science, 16 (1), 18-21 (1994). It has also been reported that the addition of ferrous salts to compositions comprising acetylsalicylic acid, or salts thereof, reduces the propensity of the compositions to induce gastric irritation. See A. Goudie, et al., U.S. Pat. No. 4,083,951.
The present invention discloses methods for protecting an oxidation-susceptible active drug ingredient or ingredients in a pharmaceutical formulation from oxidative degradation which methods comprise adding a ferrous ion source to the formulation, preferably in the form of a pharmaceutical excipient comprising the formulation components. In this manner, pharmaceutical formulations are produced in which the active drug ingredient or ingredients are protected from oxidative degradation, thus facilitating storage of the formulation over extended periods of time.
The instant invention provides methods for inhibiting oxidative degradation of pharmaceutical formulations comprising at least one oxidation-susceptible active drug ingredient which comprises protecting the formulation by the addition of an oxidation-inhibiting amount of a ferrous ion source thereto, preferably in the form of a pharmaceutical excipient.
The invention further provides pharmaceutical formulations comprising at least one oxidation-susceptible active drug ingredient and an oxidation-inhibiting amount of a ferrous iron source, preferably in the form of a pharmaceutical excipient.
The invention still further provides for the use of a ferrous ion source as an anti-oxidant in pharmaceutical formulations.